(5Z,8Z)-Tetradecadienoylcarnitine is an acyl carnitine, which is an important metabolite involved with glucose and lipid metabolism and commonly used to screen for fatty acid oxidation defects in human. Studies suggest that accumulation of acyl carnitines may associate with insulin resistance. In addition, (5Z,8Z)-Tetradecadienoylcarnitine can be used in tandem mass spectrometric analysis for amino, organic, and fatty acid disorders in newborn dried blood spots.